The invention concerns the field of glass processing, in particular, the field of the production of glass strands, such as in band form.
Glass bands are produced based on different processes. Roller pairs can be provided that are arranged in a defined manner with respect to each other and form an opening with each other, through which the glass band passes with the purpose of shaping. A float bath can also be provided.
As soon as the glass band has been shaped, it must be fed to a subsequent cooling furnace for controlled cooling. For this, a larger distance must be traveled. Rollers, a large number of which are arranged parallel to each other and perpendicular to the conveyor direction of the glass band, serve to lead and transport the glass band. The rollers are driven about their own axes. The glass band lies on these rollers. Due to the contact between the lateral surfaces of the rollers and the glass band, the rollers exert a transport effect on the glass band.
The glass of the glass band is hot on its transport path, and consequently plastic, and its surface is sensitive to damage. Thus, contact with the numerous rollers can lead to damage to the glass surface. The area between the shaping and entrance into the cooling furnace is particularly critical, since the glass is still very hot. As a rule, a roller arrangement called the “roller table” is located in this area. Hereby, for example, the firmness of the glass band can be decreased. In order to avoid this, measures must be taken that increase the firmness but that do not affect the structure of the glass in an undesired manner.
U.S. Pat. Nos. 3,615,315 and 4,081,260 describe a float process. In this process, the roller table is replaced by an air-cushion table. This avoids damage to the surface of the glass.
One disadvantage is that air cushion created by the air-cushion table exerts alone a carrying function, but not a transport function. Thus, the glass band must be transported by other means. For this reason, roller pairs are used that are either present in front of or in the furnace. The glass band is fed through the two rollers of a roller pair, hereby harnessed and pulled through the rotation of the rollers of a roller pair. The pull effect can also be exerted exclusively by the rollers located under the glass band.
As long as the glass band is intact, the pull of the pulling roller pair arranged in front of or in the furnace is sufficient. But, the glass band can come off its transport path due to its low firmness or due to certain interventions in the process at a certain point. The front section in the longitudinal direction is fed through the named roller pair into and through the cooling furnace. However, the treatment of the section, which has a glass-band beginning (leading edge portion), located behind the fracture in the longitudinal direction is problematic. A pull must be manually attached to this glass-band beginning in order to feed it into the cooling furnace to the pulling roller pair that is located there, where a pull is exerted on the beginning of the glass band and thus on the entire “new” glass band. This is extraordinarily costly; it costs time and means production downtime.